Time resolved flow velocity and concentration measurements using a travelling thermal lens

The travelling thermal lens technique is a new all optical method for probing concentration and velocity patterns in flowing media. A thermal lens created by absorption of a short laser pulse moves with the flow and can be probed by a CW laser beam further downstream as a deflection signal. This technique enables optical measurements of the flow velocity component perpendicular to the probe laser at high spatial resolution. Its application requires no seeding with particulates as needed in most other optical techniques.